Please verify that the "NFC"-feature is on in your mobile device. The option to turn on and off the NFC is usually found in the "main menu" when swiping from the top of the screen and downwards.
Example of the Android menu showing the NFC-feature to be on.
 Please note: some older phones may not even have an NFC-feature. | |
The NFC-sensor itself can be located in a few different spots on your phone and sometimes it can be a bit hard knowing exactly how to hold the phone against the tag.
On many Samsung GAlaxy-models, the sensor is located just to the right of the camera while on others, it is situated more towards the center. It may require some trial-and-error before you learn where the sensor is...

If you still can not get it to work, it may be worthwhile to restart the phone - NOTE: shut down the phone entirely rather than just doing a "regular" reboot.
If you have an iPhone:
The app should first and foremost be open. Per default, the app will open directly to scan-mode. | |
If it doesn't, simply click the Accessy-logo to activate the scan-mode. You can choose wether or not the app should open to scan-mode with the small round icon to the right of the logo. | |
When it comes to iPhones, the NFC-sensor (which is always on) is often situated on the top of the mobile phone. Try and hold the very edge of the phone towards the Accessy-tag. Sometimes it may take a bit of trial-and-error to find it.

If you still can not get it to work, it may be worthwhile to restart the phone - NOTE: shut down the phone entirely rather than just doing a "regular" reboot.